But this rapid ascent was followed by no less speedy a fall, and one act of indiscretion stripped the Athenians of all the advantages which they had acquired on the mainland of Greece. In every city of Greece there were always two parties, the wealthy and noble, called oligarchs, and the demos, or commons; and according as Spartan or Athenian influence was in the ascendant the balance of power in each city wavered between the nobles and the people, the Athenians favouring the Many, the Spartans the Few. Accordingly there was always a party living in exile, and waiting for a turn of affairs which might enable them to return to their city, and wrest the power from that faction which had been the last to triumph. In the cities of Boeotia the leaders of the oligarchs had been driven into banishment after the battle of Oenophyta, and democracies were established under the control of Athens. After nine years of banishment these exiles returned, and the result was an oligarchical reaction in the chief cities of Boeotia. A hastily equipped and ill-organised force was sent out from Athens to put down the authors of the revolution, and in the battle which followed, at Coronea, [Footnote: B.C. 447.] the Athenians sustained a severe defeat, and a large number of their citizens were taken prisoners by the Boeotians. To recover these prisoners the Athenians consented to evacuate Boeotia, and by this surrender they lost their hold on central Greece, as far as Thermopylae. This heavy blow was followed two years later by the revolt of Megara and Euboea; and in the midst of the alarm thus occasioned, the Athenians heard that a powerful Spartan army was threatening their borders. It was a terrible moment for Athens; but she was saved by the prudence and energy of Pericles, whose influence in her councils was now supreme. By some means or other--as the Spartans asserted, by a heavy bribe--he induced the Spartan king Pleistoanax to draw off his forces; and then crossing over into Euboea, he quickly reduced the whole island to submission, and took severe measures to prevent any outbreak in the future. The exertions of the Athenians during the last thirty years had been prodigious, and their efforts to found an empire in continental Greece had ended in total failure. Discouraged by their reverses, they concluded a thirty years' truce with the Spartans and their allies, resigning the last remnant of their recent conquests, and leaving Megara in her old position as a member of the Peloponnesian league under Sparta. The loss of Megara was severely felt, and her conduct in the late troubles was neither forgotten nor forgiven. The Megarians had by their own free choice been admitted into the Athenian alliance, and in an hour of great peril to Athens, without shadow of pretext they had risen in arms against her. It was not long before they had to pay a heavy penalty for their treachery and inconstancy.